Spring基于Annotation装配Bean

喜欢ヅ旅行 2023-10-07 05:18 43阅读 0赞

1、前面讲了基于XML装配Bean，为了减少XML文件的代码，将以注释的方式来解决这个问题。

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2、案例

一、人带着宠物并借助工具去砍柴:

1）砍柴的工具：斧子，锯子，电动工具。  
2）宠物有 ：猫，狗  
3）人：中国人，日本人。  
4）宠物只能带1个，工具可以带多个。  
要求输出结果：  
中国人带着狗用电动工具和斧头砍柴  
日本人带着猫用锯子砍柴

写三个接口：

package com.no4.t1.entity;
    
    public interface Animal {
        
        public String textAnimal();
    }

public interface Tool {
        
        public String chop();
    }

package com.no4.t1.entity;
    
    public interface Animal {
        
        public String textAnimal();
    }

完善三个工具类：  
@Component写在类的上方，如下Axe上，有了这个注解就相当于在Bean文件写了

package com.no4.t1.entity.impl;
    
    import org.springframework.context.annotation.Primary;
    import org.springframework.stereotype.Component;
    import com..no4.t1.entity.Tool;
    
    @Component
    @Primary //设置主候选Bean 与@Qualifier功能类似
    public class Axe implements Tool {
        
        @Override
        public String chop() {
        
            return "斧头";
        }
    }

package com.no4.t1.entity.impl;
    
    import org.springframework.stereotype.Component;
    import com.no4.t1.entity.Tool;
    @Component
    //@Primary //设置主候选Bean
    public class Saw implements Tool {
        
        @Override
        public String chop() {
        
            return "锯子";
        }
    }

package com.no4.t1.entity.impl;
    
    import org.springframework.stereotype.Component;
    import com.no4.t1.entity.Tool;
    @Component
    public class Electric  implements Tool {
        
        @Override
        public String chop() {
        
            return "电动工具";
        }
    }

完善两个宠物类

package com.no4.t1.entity.impl;
    
    import org.springframework.stereotype.Component;
    import com.no4.t1.entity.Animal;
    
    @Component
    public class Cat implements Animal {
        
        @Override
        public String textAnimal() {
        
    
            return "猫";
        }
    }

package com.no4.t1.entity.impl;
    
    import org.springframework.context.annotation.Primary;
    import org.springframework.stereotype.Component;
    import com.no4.t1.entity.Animal;
    
    @Component
    @Primary //设置主候选Bean 与@Qualifier功能类似
    public class Dog implements Animal {
        
    
          @Override
        public String textAnimal() {
        
            //System.out.println(msg);
            return "狗";
        }
    }

人的实现类

@Component
    public class Chinese implements Person {
        
        @Autowired      //写在实例变量上，可不需要setTool方法
        private Tool tool;
        private String name;
       //@Autowired 可修饰setter方法、普通方法、实例变量、构造器
        public void setTool(Tool tool) {
        
            this.tool = tool;
        }
    
        public void setName(String name) {
        
            this.name = name;
        }
    
        @Override
        public void useTool() {
        
            System.out.println("中国人"+ name + "带着狗用" + tool.chop() +"砍柴" );
        }

@Component
    public class Japanese implements Person {
        
        @Autowired
        @Qualifier("saw")   //设置默认优先选Bean
        private Tool tool;
        private String name;
    
        public void setTool(Tool tool) {
        
            this.tool = tool;
        }
        @Override
        public void useTool() {
        
            System.out.println("日本人带着猫用" + tool.chop() +"砍柴" );
        }
    }

最重要的是别忘了在其配置文件中指定搜索路径

<?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xmlns:context="http://www.springframework.org/schema/context"
           xmlns:util="http://www.springframework.org/schema/util"
           xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/util https://www.springframework.org/schema/util/spring-util.xsd">
            
            <context:component-scan base-package="com.no4.t1"/>

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